Whisk the flour, almond flour, cinnamon, and salt together in a medium bowl. Set aside.

In a large bowl using a hand mixer or stand mixer fitted with the paddle attachment, beat the butter and granulated sugar together on medium-high speed until smooth and creamy, about 2 minutes. Add the egg, vanilla extract, and lemon emulsion and beat on high speed until combined, about 1 minute. Scrape down the sides and up the bottom of the bowl as needed.

On low speed, slowly add the dry ingredients to the wet ingredients until combined. The cookie dough will be thick.

Divide the dough in half and flatten each half into a 1-inch thick disc. Wrap each disc tightly in plastic wrap and chill in the refrigerator for at least 1 hour and up to 3 days.

Preheat oven to 350°F (177°C). Line baking sheets with parchment paper or silicone baking mats.

Working with one disc at a time, roll the dough out to ⅛-inch thickness on a lightly floured surface. Cut into rounds using a 2½–3 inch fluted or plain round cookie cutter. Using a smaller 1-inch cutter (heart, star, or circle), cut a window out of half of the rounds. Re-roll scraps once.

Bake for 10–12 minutes or until the edges are very lightly browned. Allow cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.

Spread about 1 teaspoon of seedless raspberry jam on the bottom (solid) cookies. Generously dust the window cookies with confectioners’ sugar, then gently sandwich them together. The cookies will soften within a few hours — this is normal and part of their charm!